Maritime Zones and the Law of the Sea
The rights of coastal States to claim maritime zones derive from international law, the body of law that regulates the rights and duties of countries recognized by international law. The law of the sea is governed by the United Nations Convention on the Law of the Sea (UNCLOS), which defines all the maritime zones.
All maritime zones of a country are measure from its baseline. Although UNCLOS gives guidance on how a country should draw its baseline most of the countries join the points along with their coast corresponding to the Lowest Astronomical Tide (LAT) to draw their baseline and this is also accepted.
All the part of the country, which is on the LAND side of the baseline is called Internal Waters and includes rivers, estuaries, lakes, etc. Within the Internal Waters, no one can enter and a ship DOES NOT have the right to innocent passage.